Thin-film magnetic heads are used to perform both "write" and "read" operations on magnetic medias. In general, a thin-film magnetic head consists of a core of ferromagnetic material, such as permalloy, with a multi-turn coil wrapped around the core. A magnetic flux is induced in the head during "write" operations to magnetize underlying memory storage media. During "read" operations, magnetized storage media is passed by the head, inducing an electrical voltage in the coil. The induced level of electrical voltage is increased by the number of flux interactions between the permalloy and the coil. Traditionally, the increase in the number of flux interactions has been accomplished by adding more turns into the coil, by reducing the coil pitch, or adding more layers of coils. Today, a typical thin-film inductive head needs a minimum of two layers of coils to meet the performance requirements.
Typically, a multi-layer coil is fabricated by forming a first metallic coil on a substrate through either a plating process or a deposition and photo engraving process. A layer of photoresist is then spun onto the first coil and hard baked in a vacuum to insulate the first coil. Subsequent coil layers are formed over the first coil by repeating the same processes to obtain a multi-layer coil structure.
The processing time to produce and insulate each coil layer is lengthy. The processing time further increases as the number of coil layers increase. An increase in the number of coil layers also increases the process complexity. The difficulty in manufacturing a consistent multi-layer coil pattern results in low yields and higher manufacturing costs.
Accordingly, there is a continuing need for a thin-film magnetic head having multi-layer coils which can be easily produced with reduced manufacturing times and costs as well as increased manufacturing yields.